This invention relates generally to the testing of radio devices, and more specifically, to a spurious-response interference tester and method for efficiently testing the device for sensitivity to unwanted radio frequency signals.
In compliance with industry specifications, cellular receivers must conform to TIA/EIA standards. These standards require that cellular receivers be insensitive to unwanted radio frequency (xe2x80x9cRFxe2x80x9d) signals. For TDMA/AMPS dual mode cellular telephones, sections 2.3.1.4 and 2.3.2.4 of TIA/EIA-136-270-A set forth the tests required for the digital and AMPS modes of operation. In general, these tests require that the sensitivity of the receiver be monitored while an interfering signal is added. Each channel in each mode is required to be tested from the lowest RF frequency of the radio to at least 2.6 GHz in the 800 MHz bands and 6.0 GHz in the 1900 MHz bands. For a dual-band dual-mode radio, with an interferer stepping at 30 kHz, that translates to over 86,000 frequencies for each of the 832 channels for AMPS, the same number more for 800 digital, and nearly 200,000 frequencies for each of the 1998 PCS channels. This requires over 540,000,000 total tests, and, since it is based on a 30 kHz step, still does not fully comply with the TIA/EIA specification. The specification requires that every frequency be tested.
The TIA/EIA standard requires so many tests that full compliance with the standard is unreasonable and most manufacturers will not comply with the requirements. Thus, there is a need in the art for a system and method to meet the testing requirements set forth in TIA/EIA-136-270-A in a commercially reasonable manner.
One technique that has been used is to apply multiple interfering frequencies to reduce test time. While this method reduces test time, it also increases the chance of erroneously finding a failure.
Therefore, it is evident that there is a need in the art for a system and a method for testing spurious-response interference of radio devices efficiently, quickly, and accurately.
Therefore, it is also evident that there is a need in the art for a system and method for performing a test that conforms to the TIA/EIA standard and is commercially practical.
The present invention overcomes the above described problems in the prior art by providing a wideband noise source as the testing frequency in order to test large sections of the range at one time.
These wideband noise sources can be generated in various widths. This enables the total test to be performed with a lower number of iterations. If a 20 MHz wideband noise source is used, fewer than 130 iterations are needed in AMPS, fewer than 130 iterations are needed for 800 MHz digital, and fewer than 300 iterations are needed for PCS. This means that about 815,000 total tests are required.
When a test is run over a wide frequency band, the system is susceptible to errors caused by any single frequency in the band. When a failure is indicated within the band, the band is subdivided repeatedly to determine the actual frequency or frequencies causing the failure. This is done by dividing the band in half and testing each half. If an error is found in testing one of the halves, that section is further divided in half and tested again. This procedure is repeated until the band to be tested is small. When only a small band of frequencies remains, individual frequencies in the band are tested to determine the exact frequency or frequencies causing the problem. This method enables the tester to quickly eliminate large frequency bands that are immune to spurious-response interference and efficiently locate the exact frequencies at which errors occur.
Other objects, features and advantages of the present invention will become apparent upon reading the following detailed description of the embodiments of the invention, when taken in conjunction with the accompanying drawings and appended claims.